When multiple compressors are installed in the same refrigerant circuit, they are manifolded together and it becomes necessary to maintain the oil level in each compressor. There are two commonly employed arrangements for maintaining equal oil levels. First, an oil separator is used to collect oil expelled from the compressor(s) with the oil being collected in a reservoir and fed back to the compressor(s) via float valves which maintain compressor oil levels. The major disadvantages of this arrangement are that it is expensive and bulky. Second, isolate the sump of each compressor with a check valve in the end of the crankshaft and interconnect the compressors with a large tube at a sight glass port to allow oil flow between compressors. The major disadvantage of this arrangement is the need for a sealed compressor sump. With compressors using the new HFC refrigerants and polyol ester (POE) oils, a vent is desired between the sump and the suction thereby allowing pressure differences between the sumps of the compressors in the circuit. However, this can permit pulling oil out of idle compressors.